1. Field of the Invention
The present invention relates generally to the field of mechanics tools and equipment for the repair of automobiles and other motorized vehicles and more specifically to the field of devices for the disassembly of the universal joints used in the drive train of automobiles, trucks, recreational vehicles, buses, farm machinery and other machinery.
2. Description of the Prior Art
The field of devices which are used to assemble and disassemble universal joints has been studied extensively and a number of approaches have been developed. This field is important because such a device can save a mechanic a considerable amount of time during repairs to the drive train of a vehicle and avoid any damage to the universal joint during the process of assembly and disassembly. Most of the devices which are presently available to the mechanic are complex and bulky units, making them unsuitable as a tool to be carried in a mechanic's toolbox or included as a standard tool for a small garage or automotive machine shop. A review of tools and equipment for assembly and disassembly of universal joints has not revealed a simple device which incorporates features to address these problems.
One example of a device to remove and install the bearing caps of a universal joint is disclosed in U.S. Pat. No. 3,786,544, issued to Ferguson. This device consists of a sturdy rigid frame which completely encircles the universal joint during the assembly or disassembly process. The device uses a threaded rod passing through the frame to apply pressure to the bearing cups during disassembly. The end of the threaded rod opposite the universal joint is struck with a hammer to initiate a vibration in the frame much like the arms of a tuning fork to break loose a stuck bearing cap. A second press with a threaded rod located at 90 degrees to the first press is used to apply the pressure for pressing the cups back into the yoke of the universal joint. The device applies a great amount of pressure which tends to force the outer ends of the yoke toward one another, thereby creating the possibility of damaging the universal joint by permanently bending the yoke. Further, the device is very bulky and heavy. For this reason, the device is most appropriately used when bolted to the surface of a worktable.
Another example is disclosed in U.S. Pat. No. 4,805,281, issued to Stark, et al. and since abandoned. The device is a hydraulically operated apparatus for assembling universal joints. The unique features disclosed by the invention concern refinements to the hydraulic control system to insert the bearing cups of a universal joint to an accurately controlled depth in the yoke. The device is suitable only for a production environment and is much too complex and expensive for the toolbox of a mechanic or small repair facility.
U.S. Pat. No. 4,977,660, issued to Maynard, which has since been abandoned, discloses a device for supporting and positioning a universal joint for removal and installation of the bearing cups. The frame of the device consists of a base with a rigidly attached vertical member and a horizontal member attached rigidly to and extending perpendicular to said vertical member and parallel to the base. A vertical rod which slides up and down through a cavity in the horizontal member is used to apply pressure to the bearing cups of the universal joint using pressure cups of appropriate dimension in relation to the bearing cups. The frame of the device is similar to a yoke surrounding the universal joint and is bulky and heavy. Pressure for assembly and disassembly is applied through blows to the end of the vertical rod with a hammer. A pair of anvils positioned on the base of the device supports the cross of the universal joint. The pair of anvils is movable to fit universal joints of different sizes. The device is not suitable for the toolbox of most mechanics because of its size and weight. Further, it has a number of movable/removable parts which must be positioned for the removal or installation of each bearing cup of the universal joint. In addition to increasing the time required for assembly and disassembly, the use of multiple movable and removable parts increases the likelihood of a loss of key parts to the device in the normal environment of a repair facility. The pair of anvils has a flat surface on top and does not provide a cradle for the cross trunnion of a universal joint. The physical shape and size of the anvils prevents its use on the double constant velocity type of universal joint assembly. Further, for approximately 25% of the universal joints in use today, this invention will not allow the bearing cup to be pressed completely free of the yoke.
A method for installing and removing the bearing cups of a universal joint is disclosed in U.S. Pat. No. 5,836,078, issued to Aiken. The method specifically discloses a ram which may be either hydraulically or mechanically operated. Although the method used to provide the force of the ram is not claimed specifically, the invention is complex and will be heavy and bulky regardless of the specifics of the ram design for this invention. The device applies pressure to the top and bottom bearing cups simultaneously. The pressure forces the bottom bearing cup outward while the top bearing cup is forced deeper into the yoke span, requiring a separate operation to press the top bearing back to its original position then outward from the yoke. The invention appears to be geared more for a production environment and for one specific type of universal joint.
Finally, a press for inserting the bearing cups into a universal joint is found in U.S. Pat. No. 5,857,252, issued to Jansen.
The device consists of an arch or "C-shaped" member properly dimensioned to extend around the yoke of the universal joint with opposing anvil and plunger mechanism removably attached. Sufficient pressure is applied to the plunger to force the bearing cup into the universal joint.
Thus, a variety of devices to remove and install the bearing cups of a universal joint are known. Most of the devices are far too bulky and heavy to be stored in a mechanic's toolbox. The one 10 device which could be contained in a tool box disclosed in U.S. Pat. No. 5,857,252 and as previously discussed is used only for the insertion of the bearing cups for assembly of a universal joint and not for disassembly. In most cases, a mechanic can assemble a universal joint by carefully lining up the bearing cups and installing them in the yoke of the universal joint using ordinary mechanics tools. In fact, it is common practice in automotive machine and repair shops to install the bearing cups of a universal joint by simply tapping the bearing cups in place with a hammer. The problems arise when the mechanic attempts to remove the bearing cups of a universal joint that has not been disassembled for several years and has been exposed to the weather. In many cases, it is almost impossible to disassemble the universal joint without damaging the bearing cups or the yoke or both when ordinary mechanics tools are used.
Accordingly, it would be desirable to develop a simple tool which is compact and easy to store to aid a mechanic in removing the bearing cups on a universal joint. Such a device should be designed to fit a majority of the universal joints presently in use on automobiles and light trucks without adjustment.